Automatic power control (APC) of light emitting devices allows for a constant and a consistent output from these devices. Generally, automatic power control of edge emitting laser devices is easily achieved because edge emitting devices emit light from two ends. Thus, enabling one of the light emitting ends to be used to measure the power output, which is subsequently used to adjust the power input to the edge emitting device, thereby adjusting the power output.
Recently there has been an increased interest in a new type of laser device called a vertical cavity surface emitting laser (VCSEL). The VCSEL has a potential of several advantages over edge emitting lasers, such as smaller size, higher performance, and more manufacturable.
However, automatic power control of vertical cavity surface emitting lasers (VCSELs) is a difficult task because the VCSEL generally emits light from only a single surface, thus making measurement of the output and subsequent adjustment thereof a difficult task. Conventionally, in order to accomplish this task, several optical devices, such as photodiodes, mirrors, beam splitters, and the like are positioned manually in the optical path of the emission from the VCSEL. With the optical devices being positioned manually, several problems or disadvantages result, such as a high cost of manufacture, a lack of repeatability, and poor quality control, thus prohibiting high volume manufacturing.
In addition, with conventional VCSELs, driver circuitry is provided within a separate semiconductor chip. Thus, it is necessary for the interface of the light emitting device chip to a semiconductor chip that includes driver circuitry for APC. This drive circuitry enables the monitoring of the output power which is subsequently used to adjust the power input to the VCSEL, thereby adjusting the power output
It can be readily seen that conventional APC of VCSELs has several disadvantages and problems, thus not enabling their manufacture in volume manufacturing applications. Therefore, an integrated article and method for making same that simplifies the fabrication process, reduces cost, and improves reliability would be highly desirable.
It is a purpose of the present invention to provide a new and improved VCSEL semiconductor chip, including integrated drivers and photodetectors.
It is another purpose of the present invention to provide a new and improved VCSEL semiconductor chip, including integrated drivers and photodetectors, which is simple and relatively inexpensive to manufacture.
It is still another purpose of the present invention to provide a new and improved VCSEL semiconductor chip, including integrated drivers and photodetectors, which are integrated with a minimum of labor and cost.
It is a further purpose of the present invention to provide a new and improved VCSEL semiconductor chip, including integrated drivers and photodetectors, which can be utilized to control the output power of the VCSEL devices.